Animal and/or human exposures to various pollutant environments have resulted in a number of airway abnormalities. Furthermore, it has been suggested that these airway disturbances may be accentuated in atopic and/or asthmatic individuals. The purpose of these studies are to (a) investigate the possible physiologic interrelationships among pollutant induced changes in pulmonary resistance, airway reactivity to non-specific irritants, tracheal mucous velocity (as determined by a roentgenographic technique) and ciliary beat frequency (video technique) in normal conscious sheep, (b) to relate these findings to changes in the integrity of the airway epithelium (as indicated by changes in epithelial permeability to 3H-histamine), (c) to determine if these airway abnormalities are more accentuated in an animal model of allergic airway disease (allergic sheep) exposed to the same pollutant environment, (d) to determine if pollutant exposure increases the acquisition, severity and/or frequency of allergic bronchoconstriction, and (e) to attempt to relate these pollutant airway disturbances to differences in susceptibility to bacterial infection in both normal and allergic sheep. Although extrapolations of animal experiments to man are difficult, answers to these questions may uncover mechanisms responsible and consequences of pollutant induced airway abnormalities noted in both normal individuals and patients with allergic airway disease.